Systems, devices and methods for transcatheter valve delivery

ABSTRACT

A heart valve therapy system including a delivery device and a stented valve. The delivery device includes an outer sheath, an inner shaft, an optional hub assembly, and a plurality of tethers. In a delivery state, a stent frame of the prosthesis is crimped over the inner shaft and maintained in a compressed condition by the outer sheath. The tethers are connected to the stent frame. In a partial deployment state, the outer sheath is at least partially withdrawn, allowing the stent frame to self-expand. Tension in the tethers prevents the stent frame from rapidly expanding and optionally allowing recapture. Upon completion of the stent frame expansion, the tethers are withdrawn.

CROSS REFERENCE TO RELATED APPLICATIONS

This application is a continuation of U.S. application Ser. No.15/923,033, filed Mar. 16, 2018, now allowed, which is a divisional ofU.S. application Ser. No. 14/519,242, filed Oct. 21, 2014, now U.S. Pat.No. 9,925,045, which claims the benefit of the filing date of U.S.Provisional Patent Application Ser. No. 61/893,399, filed Oct. 21, 2013,the entire teachings of which are incorporated herein by reference.

BACKGROUND

The present disclosure relates to delivery devices for implantingtranscatheter valves. More particularly, it relates to catheter-baseddelivery devices and methods for implanting a prosthetic heart valvewith controlled release of the prosthesis from the delivery device.

Diseased or otherwise deficient heart valves can be repaired or replacedusing a variety of different types of heat valve surgeries. Oneconventional technique involves an open-heart surgical approach that isconducted under general anesthesia, during which the heart is stoppedand blood flow is controlled by a heart-lung bypass machine.

More recently, minimally invasive approaches have been developed tofacilitate catheter-based implantation of the valve prosthesis on thebeating heart, intending to obviate the need for the use of classicalsternotomy and cardiopulmonary bypass. In general terms, an expandableprosthetic valve is compressed about or within a catheter, insertedinside a lumen within the patient, such as the femoral artery, anddelivered to a desired location in the heart.

The heart valve prosthesis employed with catheter-based, ortranscatheter, procedures generally includes an expandable multi-levelframe or stent that supports a valve body having a plurality ofleaflets. The frame can be contracted during percutaneous transluminaldelivery, and expanded upon deployment at or within the native valve.One type of valve stent can be initially provided in an expanded oruncrimped condition, then crimped or compressed about a balloon portionof a catheter. The balloon is subsequently inflated to expand and deploythe prosthetic heart valve. With other stented prosthetic heart valvedesigns, the stent frame is formed to be self-expanding. With thesesystems, the valved stent is crimped down to a desired size and held inthat compressed state within a sheath for transluminal delivery.Retracting the sheath from this valved stent allows the stent toself-expand to a larger diameter, fixating at the native valve site.

The actual shape or configuration of any particular transcatheterprosthetic heart valve is dependent, at least to some extent, upon thevalve being replaced or repaired (i.e., mitral valve, tricuspid valve,aortic valve, or pulmonary valve). The stent frame must oftentimesprovide and maintain (e.g., elevated hoop strength and resistance toradially compressive forces) a relatively complex shape in order toachieve desired fixation with the native anatomy. With self-expandingstent designs, the stent frame can experience significant, rapid radialexpansion upon deployment from the sheath. Taken in combination, thesedesign features can give rise to delivery concerns. A rapidly expandingstent having one section expanding to a substantially larger diameterthan an adjacent section can cause the prosthetic heart valve to springoff a valve retainer of the delivery device in a relativelyun-controlled fashion. This rapid deployment can, in turn, result in thevalve section(s) forcing itself past or beyond the intended anatomicallocation. For example, exemplary prosthetic mitral valve designs canhave an inflow diameter on the order of 60 mm, with the inflow sectionof the stent frame being perpendicular, or nearly perpendicular, to ashape of the outflow section. During transluminal delivery to the nativemitral valve, the stent frame is crimped down to a nearly cylindricalshape, having a diameter on the order of 12 mm. The inflow section ofthe prosthetic mitral valve is intended to self-engage the nativeannulus, can experience rapid, uncontrolled expansion upon deployment,and may instead thrust past the native annulus and into the leftventricle.

Although there have been multiple advances in transcatheter prostheticheart valves and related delivery systems and techniques, there is acontinuing need to provide different delivery tools for controlleddeployment of the prosthesis.

SUMMARY

Some aspects of the present disclosure relate to systems for performinga therapeutic procedure on a defective heart valve, and include adelivery device and a stented prosthetic heart valve. The deliverydevice includes an outer sheath assembly, an inner shaft assembly, and aplurality of tethers. The prosthetic heart valve includes a stent framethat is configured to self-expand from a compressed condition to anormal, expanded condition. In a delivery state of the system, the stentframe is crimped over the inner shaft assembly (for example on to avalve retainer and/or a valve support), and is constrained in acompressed condition by the outer sheath assembly. Further, the tethersare connected to the stent frame, with at least one end of the tetherbeing routed proximally toward a handle assembly of the delivery device.Arrangement of the stent frame relative to the delivery device defines aproximal portion and a distal portion, with the tethers being connectedto the proximal portion or the distal portion. In some embodiments, thetethers are looped about struts or other structures provided by thestent frame. In related embodiments, a free end of each tether isconnected to a valve retainer body along the inner shaft assembly; inother embodiments, the both ends of each tether are routed to the handleassembly. In yet other embodiments, a leading end of each tether isdirectly connected to the stent frame. Regardless, during use indelivering the stented prosthetic heart valve to a native valve, thesystem is transitioned to a partial deployment state in which the sheathassembly is at least partially retracted from over the stent frame,removing the constraining force imparted upon the stent frame. Theexposed portion(s) of the stent frame self-expand toward the normal,expanded condition, with a tension in the tethers preventing thecorresponding region of the stent frame from rapidly expanding. Uponattaining complete expansion, the delivery device is transitioned to afull deployment state in which the tethers are withdrawn from the stentframe. In some embodiments, the systems and devices of the presentdisclosure provide for recapture of an expanded stent frame prior torelease of the tethers, for example by re-tensioning the tethers toeffectuate at least partial compression or re-collapsing of thecorresponding region of the stent frame. The stent frame can then moreeasily be received within a separate recapture sheath or the deliverysheath.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1A is a side view of an exemplary stented prosthetic heart valveuseful with systems, devices and methods of the present disclosure andin a normal, expanded condition;

FIG. 1B is a side view of the prosthetic heart valve of FIG. 1A in acompressed condition;

FIG. 2 is a side view of another exemplary prosthetic heart valve stentuseful with systems, devices and methods of the present disclosure andin a normal, expanded condition;

FIG. 3A is an exploded perspective view of a stented prosthetic heartvalve delivery device in accordance with principles of the presentdisclosure;

FIG. 3B is a side view of the delivery device of FIG. 3A;

FIG. 4A is a simplified, cross-sectional view of a portion of a deliverydevice in accordance with principles of the present disclosure, loadedwith a stented prosthetic heart valve and in a delivery state;

FIGS. 4B-4E illustrate operation of the delivery device of FIG. 4A intransiting to a partial deployment state and a full deployment state;

FIG. 5A is a simplified side view of valve retainer and tethercomponents useful with delivery devices of the present disclosure and ina captured arrangement;

FIG. 5B is a side view of the components of FIG. 5A and in a releasedstate;

FIG. 5C is a side view of another valve retainer useful with deliverydevices of the present disclosure;

FIG. 5D is a side view of another valve retainer useful with deliverydevices of the present disclosure;

FIGS. 6A-6C are simplified side views illustrating operation of anotherembodiment delivery device in accordance with principles of the presentdisclosure in conjunction with a prosthetic heart valve stent frame;

FIG. 7A is a side view of a portion of another embodiment prostheticheart valve stent frame useful with delivery devices of the presentdisclosure in a compressed condition, along with a tether;

FIG. 7B is a simplified side view of the arrangement of FIG. 7A, withthe stent frame in a normal, expanded condition;

FIG. 8A is a perspective view of a portion of another embodimentdelivery device in accordance with principles of the present disclosure,along with a portion of prosthetic heart valve stent frame in acompressed condition;

FIG. 8B is a cross-sectional view of a portion of the delivery device ofFIG. 8A;

FIG. 9A is a perspective view a portion of the assembly of FIG. 8A in apartial deployment state;

FIG. 9B is a perspective view of the arrangement of FIG. 9A and in asubsequent stage of partial deployment;

FIG. 10A is a perspective view of another embodiment system inaccordance with principles of the present disclosure, including adelivery device loaded with a prosthetic heart valve stent frame and ina delivery state;

FIG. 10B is a perspective view of the system of FIG. 10A in a partialdeployment state and immediately prior to full deployment of the stentframe;

FIG. 10C is a perspective view of the prosthetic heart valve of FIG.10A;

FIG. 10D is a perspective view of the system of FIG. 10A and in adelivery state;

FIG. 11A is a perspective view of the system of FIG. 10A andillustrating transitioning of the system toward the arrangement of FIG.10B;

FIG. 11B is an enlarged, perspective view of a portion of FIG. 11A;

FIGS. 12A-12C are simplified perspective views of a portion of a controlshaft and tether useful with the system of FIG. 11A; and

FIGS. 13A-15D illustrate use of the system of FIG. 11A, includingoperation of the delivery device in deploying the stent frame to anative mitral valve.

DETAILED DESCRIPTION

As referred to herein, stented transcatheter prosthetic heart valvesuseful with and/or as part of the various systems, devices and methodsof the present disclosure may assume a wide variety of differentconfigurations, such as a bioprosthetic heart valve having tissueleaflets or a synthetic heart valve having polymeric, metallic ortissue-engineered leaflets, and can be specifically configured forreplacing any of the four valves of the human heart. Thus, the stentedprosthetic heart valve useful with the systems, devices, and methods ofthe present disclosure can be generally used for replacement of a nativeaortic, mitral, pulmonic or tricuspid valve, or to replace a failedbioprosthesis, such as in the area of an aortic valve or mitral valve,for example.

In general terms, the stented prosthetic heart valves of the presentdisclosure include a stent or stent frame having an internal onemaintaining a valve structure (tissue or synthetic), with the stentframe having a normal, expanded condition or arrangement and collapsibleto a compressed condition or arrangement for loading within a deliverydevice. The stent frame is normally constructed to self-deploy orself-expand when release from the delivery device. For example, thestents or stent frames are support structures that comprise a number ofstruts or wire segments arranged relative to each other to provide adesired compressibility and strength to the prosthetic heart valve. Thestruts or wire segments are arranged such that they are capable ofself-transitioning from a compressed or collapsed condition to a normal,radially expanded condition. The struts or wire segments can be formedfrom a shape memory material, such as a nickel titanium alloy (e.g.,Nitinol™). The stent frame can be laser-cut from a single piece ofmaterial, or can be assembled from a number of discrete components.

With the above understanding in mind, one simplified, non-limitingexample of a stented prosthetic heart valve 30 useful with systems,devices and methods of the present disclosure is illustrated in FIG. 1A.As a point of reference, the prosthetic heart valve 30 is shown in anormal or expanded condition in the view of FIG. 1A; FIG. 1B illustratesthe prosthetic heart valve in a compressed condition (e.g., whencompressively retained within an outer catheter or sheath as describedbelow). The prosthetic heart valve 30 includes a stent or stent frame 32and a valve structure 34. The stent frame 32 can assume any of the formsmentioned above, and is generally constructed so as to beself-expandable from the compressed condition (FIG. 1B) to the normal,expanded condition (FIG. 1A).

The valve structure 34 can assume a variety of forms, and can be formed,for example, from one or more biocompatible synthetic materials,synthetic polymers, autograft tissue, homograft tissue, xenografttissue, or one or more other suitable materials. In some embodiments,the valve structure 34 can be formed, for example, from bovine, porcine,equine, ovine and/or other suitable animal tissues. In some embodiments,the valve structure 34 can be formed, for example, from heart valvetissue, pericardium, and/or other suitable tissue. In some embodiments,the valve structure 34 can include or form one or more leaflets 36. Forexample, the valve structure 34 can be in the form of a tri-leafletbovine pericardium valve, a bi-leaflet valve, or another suitable valve.In some constructions, the valve structure 34 can comprise two or threeleaflets that are fastened together at enlarged lateral end regions toform commissural joints, with the unattached edges forming coaptationedges of the valve structure 34. The leaflets 36 can be fastened to askirt that in turn is attached to the frame 32. The upper ends of thecommissure points can define an inflow portion 38 corresponding to afirst or inflow end 40 of the prosthesis 30. The opposite end of thevalve can define an outflow portion 42 corresponding to a second oroutflow end 44 of the prosthesis 30. As shown, the stent frame 32 canhave a lattice or cell-like structure, and forms or provides crowns 46and/or eyelets 48 (or other shapes) at the outflow and inflow ends 40,44.

With the but one acceptable construction of FIGS. 1A and 1B, theprosthetic heart valve 30 can be configured (e.g., sized and shaped) forreplacing or repairing an aortic valve. Alternatively, other shapes arealso envisioned, adapted to mimic the specific anatomy of the valve tobe repaired (e.g., stented prosthetic heart valves useful with thepresent disclosure can alternatively be shaped and/or sized forreplacing a native mitral, pulmonic or tricuspid valve). For example,FIG. 2 illustrates another non-limiting example of a stent frame 50portion of another prosthetic heart valve with which the systems,devices and methods of the present disclosure are useful. In the normalor expanded condition of FIG. 2, the stent frame 50 can be sized andshaped for mitral valve implantation. Though not shown, the valvestructure attached to the stent frame 50 defines an outflow portion 52arranged at a first or outflow end 54, and an inflow portion 56 arrangedat a second or inflow end 58. As compared to the stent frame 32 of FIG.1A, the inflow portion 56 can exhibit a more pronounced change in shaperelative to the corresponding outflow portion 52. Regardless, the stentframe 50 can be forced and constrained to a compressed condition (notshown, but akin to the shape of FIG. 1A) during delivery, and willself-expand to the natural condition of FIG. 2 upon removal of theconstraining force(s). As a point of reference, in some constructions,the stent frame 50 is configured to be crimped to a diameter on theorder of 12 mm during delivery, and will self-expand to the natural,expanded condition that includes the inflow portion 56 having a diameteron the order of 60 mm. As reflected in FIG. 2, crowns 60 and/or eyelets62 (or other shapes) can be formed at one or both of the outflow andinflow ends 54, 58. Further, the stent frame 50 can optionally includeor carry additional structural components, such as support arm(s) 64.

With the above understanding of the stented prosthetic heart valves inmind, one embodiment of a delivery device 70 for percutaneouslydelivering the prosthesis is shown in simplified form in FIGS. 3A and3B. The delivery device 70 includes a delivery sheath assembly 72, aninner shaft assembly 74, a hub assembly 76, one or more tethers 78, anda handle assembly 80. Details on the various components are providedbelow. In general terms, however, the delivery device 70 combines with astented prosthetic heart valve (not shown) to form a system forperforming a therapeutic procedure on a defective heart valve of apatient. The delivery device 70 provides a loaded or delivery state inwhich a stented prosthetic heart valve is coupled to the inner shaftassembly 74 via the hub assembly 76 and compressively retained within acapsule 82 of the delivery sheath assembly 72. For example, the hubassembly 76 can include or provide one or both of a valve support 83 anda valve retainer 84. The valve retainer 84 is configured to selectivelyreceive a corresponding feature (e.g., posts) provided with theprosthetic heart valve stent frame, whereas the valve support 83provides an increased diameter (as compared to a diameter of the innershaft assembly 74) for directly supporting a portion of a length of thestent frame in the compressed condition. The valve support 83 and thevalve retainer 84 can be formed as separate components, or can beintegrally formed. In yet other embodiments, the hub assembly 76 doesnot include the valve support 83, or does not include the valve retainer84. As used throughout this disclosure, then, a “hub assembly component”is in reference to a valve support, a valve retainer, or both, and thecorresponding delivery device need only include one of the valve supportor the valve retainer. The tether(s) 78 connect an end of the stentedprosthetic heart valve to a remainder of the delivery device 70, forexample to the hub assembly 76. The delivery sheath assembly 72 can bemanipulated to withdraw the capsule 82 proximally from over theprosthetic heart valve via operation of the handle assembly 80,permitting the prosthesis to self-expand and partially release from theinner shaft assembly 74 in a partial deployment state. In the partialdeployment state, the tether(s) 78 maintain connection between theprosthesis and the delivery device 70 (e.g., connection with the hubassembly 76) such that expansion of the corresponding portion or end ofthe stented prosthetic heart valve is controlled and/or is less thancomplete in some embodiments. In other embodiments, the tether(s) 78slowly self-releases from the stent frame as the stent frame expands ina manner that reduces the rate at which expansion occurs (e.g., thetethers 78 effectuate slow release of the stent frame from the deliverydevice 70). With configurations in which the tether(s) 78 remainsconnected to the stent frame upon retraction of the capsule 82, thetether(s) 78 can optionally be subjected to increased tension, causingthe corresponding portion of the stent frame to at least partiallyre-collapse or compress, making recapture of the stent frame possible(e.g., recapture within a separate recapture sheath (not shown) advancedover the delivery sheath assembly 72, or back within the capsule 82). Ina deployment state, the tether(s) 78 is removed from engagement with theprosthesis, permitting the stented prosthetic heart valve to completelyrelease or deploy from the delivery device 70.

Various features of the components 72-80 reflected in FIGS. 3A and 3Band as described below can be modified or replaced with differingstructures and/or mechanisms. Thus, the present disclosure is in no waylimited to the delivery sheath assembly 72, the inner shaft assembly 74,the hub assembly 76 or the handle assembly 80 as shown. Any constructionthat generally facilitates compressed loading of a stented prostheticheart valve over an inner shaft via a retractable outer sheath orcapsule is acceptable. For example, the capsule 82 may be a discretecomponent of the delivery sheath assembly 72, or can be morehomogeneously formed as part of a continuous outer sheath. The innershaft assembly 74 can integrally form the hub assembly 76 (including oneor both of the valve support 83 and the valve retainer 84) and canterminate in a dilator tip 86. Further, the tether(s) 78 can also assumea wide variety of forms and arrangements relative to a remainder of thedelivery device 70 as described below. The tether(s) 78 can be a suture,thread, thin wire, or other elongated, flexible body. Finally, thedelivery device 70 can include additional components or features, suchas a flush port assembly 88, a recapture sheath (not shown), etc.

In more general terms, a simplified representation of one embodiment ofthe delivery device 70 in the delivery state and loaded with a stentedprosthetic heart valve 90 (referenced generally) to provide a system 92for performing a therapeutic procedure on a defective heart valve isprovided in FIG. 4A. For ease of illustration, only the stent frame 50of the prosthesis 90 is depicted in FIG. 4A. The stent frame 50 iscrimped over the inner shaft assembly 74, and is compressibly held inthe compressed condition by the capsule 82. The prosthesis 90 isarranged such that the inflow end 58 is proximal the outflow end 54. Asloaded to the delivery device 70, then, the inflow end 58 can be viewedas the proximal end of the prosthesis 90, and the outflow end 54 as thedistal end. In other embodiments, an orientation of the prosthetic heartvalve 90 can be reversed relative to the delivery device 70. One or moreof the tethers 78 are connected to the proximal end 58. For example, inthe view of FIG. 4A, two of the tethers 78 are provided, it beingunderstood that in other embodiments, only a single tether 78 or morethan two of the tethers 78 is included. Each of the tethers 78 defines aleading end 94 opposite a trailing end (not shown). A leading segment 96is defined immediately adjacent the leading end 94. With thesedesignations in mind, the leading segment 96 is looped through a portionof the stent frame 50 at or adjacent the proximal end 58, for examplethrough one of the crowns 60 or eyelets 62 (FIG. 2). The leading end 94is connected to the hub assembly 76 (e.g., at a valve retainer such asthe valve retainer 84 (FIG. 3A)), with the capsule 82 (or other portionof the delivery sheath assembly 72) serving to capture the leading end94 to the hub assembly 76. The trailing end of each of the tethers 78can be positioned in various locations, and in some embodiments isrouted proximally to the handle assembly 80 (FIGS. 3A and 3B). In thisregard, the hub assembly 76 can form a corresponding number ofpassageways through which the tethers 78 extend, respectively.

Following transluminal delivery of the compressed prosthesis 90 to thetargeted native valve (via the delivery device 70 in the delivery stateof FIG. 4A), the delivery device 70 is operated to deploy the stentedprosthetic heart valve 90 by proximally retracting the capsule 82. FIG.4B illustrates an initial stage of deployment in which the capsule 82has been partially retracted from over the prosthesis 90. As shown, aportion of the prosthesis 90 is still within the capsule 82 (e.g., adistal end 100 of the capsule 82 is distal the proximal end 58 of thestented prosthetic heart valve 90). The now-exposed segment of theprosthesis 90 distal the capsule 82 self-expands to or toward the normalor expanded condition. That portion of the prosthesis 90 still withinthe confines of the capsule 82 remains in the compressed condition andis thus still captured or robustly connected to the delivery device 70.Further, the capsule 82 maintains the captured arrangement of thetethers 78 with the hub assembly 76, and thus with the stent frame 50.

Proximal retraction of the capsule 82 continues. In the partialdeployment state of FIG. 4C, the distal end 100 of the capsule 82 is nowproximal to the proximal end 58 of the stent frame 50, but is distal thelocation of connection between the leading end 94 of each of the tethers78 with the hub assembly 76. Thus, the tethers 78 maintain theconnection of the prosthesis 90 with the delivery device 70. In thisregard, the tethers 78 are held in tension (e.g., the trailing end (notshown) of each of the tethers 78 is located at the handle assembly 80(FIGS. 3A and 3B), and coupled to a corresponding component(s) providedtherewith). The tensioned tethers 78 serve to control expansion of theproximal end 58. More particularly, were the tethers 78 not present, thestent frame 50, and in particular the proximal end 58, would freelyself-expand to the normal, expanded condition shown in FIG. 2. Thetensioned tethers 78 prevent this self-expansion from rapidly occurring.Instead, tension in the tethers 78 is slowly released, allowing theproximal end 58 to more slowly transition toward the normal, expandedcondition, as generally reflected in FIG. 4D. As described below, thehandle assembly 80 optionally includes one or more mechanisms that allowa user to control tension in the tethers 78.

Once tension in the tethers 78 has been sufficiently lessened to permitthe proximal end 58 to self-expand to the normal, expanded condition,the capsule 82 is further proximally retracted, locating the distal end100 proximal the leading end 94 of each of the tethers 78. As shown inFIG. 4E, the tethers 78 are now no longer captured relative to the hubassembly 76, and can be removed from engagement with the stent frame 50by, for example, proximally withdrawing the tethers 78 through thedelivery device 70. Alternatively, the delivery device 70 can beconfigured to effectuate release of the tethers 78 from the hub assembly76 apart from movement of the capsule 82 as described below. Regardless,with embodiments in which the tethers 78 remain robustly connected withthe stent frame 50, as the stent frame 50 is allowed to expand (e.g.,the looped connection described above) at any point prior to release ofthe leading end 94, the tethers 78 can be manipulated to perform arecapture procedure. For example, tension in the tethers 78 can beincreased, causing the proximal end 58 to re-collapse or compress (e.g.,transition from the expanded condition of FIG. 4D to or toward thecompressed condition of FIG. 4C). Once the proximal end 58 isre-collapsed, an entirety of the stent frame 50 can more easily becompressed and recaptured relative to the delivery device 70, forexample within a separate recapture sheath (not shown) slidably advancedover the capsule 82 (e.g., the delivery device 70 can be retractedrelative to the recapture sheath to bring the stent frame 50 within therecapture sheath or the recapture sheath can be distally advanced overthe stent frame 50) or by advancing the capsule 82 over the stent frame50. Regardless, in the full deployment state of FIG. 4E, the stentedprosthetic heart valve 90 is fully released from the delivery device 70.

The hub assembly component(s) and/or the tethers 78 can assume a varietyof forms that facilitate temporary coupling there between pursuant tothe above descriptions. For example, FIG. 5A illustrates one embodimentof a tether 120 and a valve retainer 122 (that can be provided with thehub assembly 76 of FIG. 3A) useful with delivery devices of the presentdisclosure. The tether 120 forms or provides a ball 124 at a leading end126 thereof. The valve retainer 122 forms or defines a retention hole128 and a guide slot 130 extending from the hole 128 to a distal end 132of the valve retainer 122. The ball 124 can be generated in a variety ofmanners. For example, where the tether 120 is a conventional suture, theball 124 can be a knot formed in the suture, or can be formed by meltingthe leading end 126. In other embodiments, the ball 124 is aseparately-formed body that is attached (e.g., adhesive, weld, etc.) tothe tether 120. Regardless, the retention hole 128 is sized toselectively receive the ball 124, and the guide slot 130 is sized toaccommodate a thickness of the tether 120. As a point of reference, withembodiments including two or more of the tethers 120, the valve retainer122 will form a corresponding number of the capture retention holes128/guide slots 130.

In the assembled arrangement of FIG. 5A, the capsule 82 secures the ball124 within the retention hole 128. With proximal retraction of thecapsule 82 to the arrangement of FIG. 5B, the distal end 100 of thecapsule 82 is moved proximal the ball 124, allowing the tether 120 torelease from the valve retainer 122 as described above.

In some embodiments, the valve retainer 122 can incorporate variousfeatures that assist in loading the prosthesis (not shown) to thedelivery device, and in particular connecting the tether(s) 120 with thevalve retainer 122. As a point of reference, where the particulardelivery device incorporates a plurality of the tethers 120, it can bedifficult to loop the tethers 120 through the stent frame and then holdall of the tethers 120 in place relative to the valve retainer 122 whilesimultaneously locating the assembly within the capsule 82. With this inmind, in some embodiments, the guide slot 130 is optionally provided andis formed to a width approximating a diameter of the tether 120. Withthis construction, the tether 120 will be frictionally held within thecorresponding slot 130 during loading. Notably, however, the frictionalforce or interface between the tether 120 and the valve retainer 122 atthe slot 130 is significantly less than the expected radially-outwardforce applied onto the tether 120 by the stent frame (not shown) inself-expanding from the compressed condition to the normal, expandedcondition. Thus, the tether 120 will readily disengage from the slot 130during deployment.

FIG. 5C illustrates another embodiment valve retainer 122A useful withdelivery devices of the present disclosure, and is akin to the valveretainer 122 (FIG. 5A) described above. As shown, the valve retainer122A forms a plurality of the retention holes 128 a-128 c for retaininga corresponding number of the tethers (not shown). The retention holes128 a-128 c are offset from one another in a spiral configuration. Withthis construction, loading of the prosthesis (not shown) can includelooping a first tether (not shown) through the stent frame and locatingthe corresponding leading end within the first retention hole 128 a. Thecapsule (not shown) is then distally advanced over the first retentionhole 128 a to capture the first tether. However, the remaining retentionholes 128 b, 128 c remain uncovered. The process is repeated tosequentially secure second and third tethers (not shown) to the secondand third retention holes 128 b, 128 c.

FIG. 5D illustrates another embodiment valve retainer 122B useful withdelivery devices of the present disclosure, and is akin to the valveretainer 122 (FIG. 5A) described above. As shown, the valve retainer122B forms or defines a plurality of enlarged retention holes 140 (oneof which is shown in FIG. 5D). As compared to dimensions of theretention hole 128 of FIG. 5A, the enlarged retention holes 140 have anelevated length, but are sized (width) to house the tether leading end(not show, but for example the ball 124 of FIG. 5A). During loading, thecapsule (not shown) is advanced partially over the valve retainer 122Bso as to cover a proximal segment of each the retention holes 140. Asmall gap remains between the capsule and the distal end of the each ofthe retention holes. The tethers (not shown) are then looped through thestent frame (not shown), and the corresponding leading end forced orpushed through the gap and into the covered, proximal segment of thecorresponding retention hole 140.

The valve retainers or other hub assembly components of the presentdisclosure can incorporate other features conducive to selectivelyretaining a leading end of the tether(s). In other embodiments of thepresent disclosure, the delivery device can include one or more featuresthat promote release of the tether leading end from the hub assembly.

While several of embodiments of the present disclosure couple a leadingend of the tether(s) to the retainer, in other constructions thetether(s) is not directly connected to the retainer. For example, FIGS.6A-6C illustrate, in simplified form, portions of another deliverydevice 200 in accordance with principles of the present disclosure andincluding a delivery sheath assembly 202 and a plurality of tethers 204.The delivery device 200 is shown relative to a prosthetic heart valve206 having a stent frame 208, with the delivery device 200 and theprosthesis 206 combining to provide a system 210 in accordance withprinciples of the present disclosure. In the delivery state of FIG. 6A,each of the tethers 204 is looped through a proximal portion 212 of thestent frame 208 such that the tethers 204 can be viewed as definingopposing, first and second tether segments 214, 216. The tether segments214, 216 are routed proximally through the delivery sheath assembly 202,for example through passageways in an inner shaft assembly (not shown),to a handle assembly (not shown) of the delivery device 200.

In the partial deployment state of FIG. 6B, the delivery sheath assembly202 has been proximally retracted from over the prosthetic heart valve206, allowing regions of the stent frame 208 to self-expand toward thenatural, expanded condition. The tethers 204 remain connected to thestent frame 208 and are under tension, thus impeding rapid, completeexpansion of the proximal portion 212. As tension in the tethers 204 isreleased, the proximal portion 212 is allowed to self-expand toward thenormal condition in a controlled fashion, as represented by FIG. 6C.Once the stent frame 208 has completely expanded, the tethers 204 can beremoved, for example by pulling on either the first or second tethersegment 214, 216 of each of the tethers 204. At any point prior torelease of the tethers 204 from the stent frame 208, tension in thetethers 204 can be increased to at least partially re-collapse theproximal portion 212 as part of an optional recapture operation.

While some embodiments described above generally entail looped-typeconnection of the tether(s) relative to the corresponding prostheticheart valve stent frame, in other constructions, the tether can be morerobustly connected to, or terminate at, the stent frame. Self-releasing,temporary engagement between the tether leading end and the stent framecan be provided in a variety of manners. One or more tethers can betemporarily connected to the corresponding prosthetic heart valve stentframe in a looped, twisted or wrapped manner. Further, the stent framecan incorporate one or more additional features that better ensurecomplete unwinding of the tether upon full deployment of the stentframe. For example, portions of another system 300 in accordance withprinciples of the present disclosure are shown in simplified form inFIGS. 7A and 7B. The system 300 includes a prosthetic heart valve stentframe 310 useful with delivery devices of the present disclosure. Thestent frame 310 includes a conventional cell structure 312 defined, atleast in part, by opposing, first and second strut segments 314, 316. Afirst barb 318 extends from the first strut segment 314, and a secondbarb 320 extends from the second strut segment 316. The barbs 318, 320are sized and shaped such that in the compressed condition of the stentframe 310 reflected by FIG. 7A, the barbs 318, 320 cross over oneanother to generate a capture zone 322. In the compressed condition ofFIG. 7A, the capture zone 322 is “closed,” completely bounded, at leastin the proximal direction, by the barbs 318, 320. The barbs 318, 320 arefurther configured such that in the normal, expanded condition of thestent frame 310, the capture zone 322 is open as shown in FIG. 7B.

With the above construction, with the stent frame 310 in the compressedcondition, a tether 324 can be wound or twisted about the stent frame310 and temporarily secured thereto via the closed capture zone 322.This connection is shown in FIG. 7A. As the tether 324 allows the stentframe 310 to slowly self-expand toward the normal, expanded condition asdescribed above, the barbs 318, 320 spatially move relative to oneanother to “open” the capture zone 322. As shown in FIG. 7B, then, uponfull deployment of the stent frame 310, the tether 324 is released fromthe capture zone 322 and freely unwinds from the stent frame 310.

Connection between the tether(s), prosthetic heart valve stent frame,and other components of the delivery device can assume a variety formsin accordance with the present disclosure. For example, FIG. 8Aillustrates a portion of another system 390, including anotherembodiment delivery device 400 and a prosthetic heart valve stent frame402. The delivery device 400 includes a delivery sheath assembly 404, aninner shaft assembly 405 (primarily hidden in FIG. 8A, but shown inFIGS. 8B and 9A), a hub assembly including a valve support 406 and avalve retainer 408, and a plurality of tethers 410. The valve retainer408 is attached to, or formed by, the inner shaft assembly 405, andforms a plurality of posts 412 (one of which is visible in FIG. 8A). Agroove 414 is defined about each of the posts 412, and is sized topermit winding of a corresponding one of the tethers 410 around the post412. In the delivery state generally reflected by FIG. 8A, each of thetethers 410 extends from the corresponding post 412 and is loopedthrough the stent frame 402. For example, relative to the tether 410identified in FIG. 8A, the tether 410 is looped through or around twocrowns 416 formed at a proximal portion 418 of the stent frame 402. FIG.8B is a simplified cross-sectional view of a portion of the deliverydevice 400, and reflects that the tether 410 is looped about thecorresponding post 412, effectively defining first and second tethersegments 410 a, 410 b extending from the post 412. The tether segments410 a, 410 b are connected to the stent frame 402 (FIG. 8A) and thenrouted proximally to and optionally through at least the valve retainer408. The tether segments 410 a, 410 b can extend to a handle assembly(not shown) of the delivery device 400 or can be connected to anothercomponent of the delivery device 400 adapted to facilitate user controlover a tension in the tether 410.

With the above construction in mind and returning to FIG. 8A, thedelivery sheath assembly 404 serves to retain the tethers 410 relativeto the corresponding post 412. As a point of reference, FIG. 8Aillustrates a distal end 420 of the delivery sheath assembly 404 asbeing proximal the posts 412 for ease of illustration. In the deliverystate of the delivery device 400, however, the distal end 420 is distalthe posts 412 so as to maintain engagement of the tethers 410 with theposts 412. Further, as with previous embodiments, in the delivery statethe distal end 420 is located distal the stent frame 402 to constrainthe stent frame 402 to the compressed condition.

FIG. 9A depicts the delivery device 400 in the initial stages of apartial deployment state. The distal end 420 of the delivery sheathassembly 404 is proximal a significant portion of the stent frame 402,such that stent frame 402 self-expands toward the normal, expandedcondition. However, the distal end 420 remains distal each of the tether410/post 412 interfaces such that each of the tethers 410 remainsconnected to the corresponding stent frame 402. Tension in the tethers410 resists rapid expansion of the proximal portion 418. As reflected byFIG. 9B, the tethers 410 allow the proximal portion 418 to slowly attainthe normal, expanded condition. The tethers 410 remain connected to thecorresponding posts 412 within the delivery sheath assembly 404. Undercircumstances where a user desires to recapture the stent frame 402 forre-deployment at another anatomical location or removal from thepatient, tension in the tethers 410 can be increased to cause theproximal portion 418 to at least partially re-collapse or compress backtoward the compressed condition. This action, in turn, facilitatesrecapture of an entirety of the stent frame 402 within a separaterecapture sheath (not shown), for example by advancing the recapturesheath over the delivery sheath assembly 404; the delivery system 390can then be retracted to bring the stent frame 402 into the recapturesheath, or the recapture sheath can be advanced over the partiallycollapsed stent frame 402. In other recapture operations, the partiallycollapsed stent frame 402 can be reinserted back within the deliverysheath assembly 404.

While several of the above embodiments connect the tether(s) at oradjacent a proximal portion of the corresponding prosthetic heart valvestent frame, in other constructions, a more distal connection can beprovided. For example, portions of another embodiment system 500 forperforming a therapeutic procedure on a patient's heart are shown inFIGS. 10A-10B. The system 500 includes a delivery device 502 and aprosthetic heart valve 504 (referenced generally). As a point ofreference, only a stent frame assembly 506 of the prosthetic heart valve504 is illustrated in several of the views. FIG. 10A reflects the stentframe assembly 506 loaded to the delivery device 502 and is indicativeof a delivery state. FIG. 10B depicts the stent frame assembly 506partially deployed from the delivery device 502 (and alternatively canbe viewed as an initial stage of loading the stent frame assembly 506 tothe delivery device 502).

The delivery device 502 includes an outer sheath assembly 510, an innershaft assembly 512, and a plurality of tethers 514. The delivery sheathassembly 510 includes or forms a capsule 516 terminating at a distal end518. As with previous embodiments, the delivery sheath assembly 510 iscoaxially received over the inner shaft assembly 512, and islongitudinally slidable relative to the inner shaft assembly 512.

A identified in FIG. 10B, the inner shaft assembly 512 includes aprimary shaft 530 and carries a valve retainer (or other hub assemblycomponent) 532. The primary shaft 530 forms or defines a plurality ofside lumens 534 (referenced generally) sized to receive respective onesof the tethers 514. An optional central guide lumen 536 (referencedgenerally) is also provided, and through which an optional secondaryshaft 538 is disposed. The secondary shaft 538 extends distally from theprimary shaft 530, and is attached to or forms a dilator tip 540. Insome embodiments, the dilator tip 540 and the secondary shaft 538 definea common guidewire lumen 542.

The valve retainer 532 can assume a variety of forms, and is attached tothe primary shaft 530. In general terms, the valve retainer 532incorporates one or more features commensurate with components of stentframe assembly 506 that facilitate mounting of the stent frame assembly506 to the inner shaft assembly 512. For example, and as best shown inFIG. 10B, the valve retainer 532 can form one or more slots 544 sizedand shaped to receive a corresponding component of the stent frameassembly 506.

The plurality of tethers 514 can assume any of the forms described above(e.g., threads, sutures, thin wires, etc.), and are slidably disposedwithin respective ones of the side lumens 534. In some embodiments, theprimary shaft 530 routes each of the tethers 514 proximally to a handleassembly (not shown) provided with the delivery device 502, with thehandle assembly, in turn, including one or more mechanisms configured toprovide user control over ends of each of the tethers 514 and/or tensionwithin the tethers 514.

With additional reference to FIG. 10C, the stent frame assembly 506 canassume a variety of forms and some embodiments includes a stent frame550 and a plurality of support arms 552. The stent frame 550 carries avalve structure 553 provided with the prosthetic heart valve 504, and isconfigured to self-expand from a compressed condition (such as thecompressed condition of FIG. 10A) to the normal, expanded condition (ofFIG. 10C). The stent frame 550 further defines various features thatpromote connection with the delivery device 502 and/or the valvestructure 553, as well as desired interface with native anatomy of theheart valve being treated. For example, the stent frame 550 can form ordefine posts 554 and crowns 556. Relative to an orientation of the stentframe assembly 506 upon mounting to the delivery device 502, the posts554 are located at a proximal end 558 of the stent frame 550, whereasthe crowns 556 are at a distal end 560. The crowns 556 can have variousformats, and in some embodiments are akin to an eyelet that defines anaperture 562 (identified for one of the crowns 556 in FIGS. 10A and10B).

The support arms 552 are optionally provided with the stent frameassembly 506, extending outwardly from the stent frame 550. The supportarms 552 can each have generally curved shape shown, and are configuredto interface with structures of the native valve anatomy, such as thenative leaflets.

Assembly of the system 500 includes locating the stent frame assembly506 over the inner shaft assembly 512, and then connecting each of thetethers 514 to the distal end 560 of the stent frame 550. For example,each of the tethers 514 is looped through a respective one of the crowns556 (via the corresponding aperture 562). The tethers 514 are routedthrough corresponding ones of the side lumens 534 proximally to thehandle assembly (not shown). The stent frame assembly 506 is crimped orcompressed onto the inner shaft assembly 512. For example, the posts 554can be located within respective ones of the slots 544 provided with thevalve retainer 532. In the compressed condition, the stent frameassembly 506 is loaded within the capsule 516 as generally reflected inFIG. 10A and fully shown in FIG. 10D. Any slack in the tethers 514 isremoved, and the tethers 514 are then locked. In this held arrangement,the tethers 514 prevent or impede radial self-expansion of the distalend 560.

During use, the prosthetic heart valve 504 can be deployed from thedelivery device 502 in a progressive fashion. For example, FIG. 11Aillustrates an initial stage of deployment. The capsule 516 has beenproximally retracted relative to the stent frame assembly 506, locatingthe distal end 518 proximal the support arms 552. As shown, once removedfrom the confines of capsule 516, the support arms 552 self-expand to ortoward the normal, expanded condition. While a substantial portion ofthe stent frame 550 is also now distal the capsule 516 and thus free ofthe constraints presented by the capsule 516, the tethers 514 prevent orimpede self-expansion of the stent frame 550, at least at the distalportion 560. As shown in greater detail in FIG. 11B, the tethers 514remain connected to the stent frame 550 at the crowns 556. Because thetethers 514 are locked, the tethers 514 are placed in tension by thestent frame 550, and prevent overt radial expansion of the distalportion 560. While regions of the stent frame 550 proximal the distalportion 560 may experience some minor expansion, the stent frame 550 isessentially maintained in the compressed condition.

When desired, tension in the tethers 514 can be progressively lessened,thereby permitting the distal portion 560 to self-expand. In someembodiments, the tethers 514 can be removed by simply pulling on one endof each of the tethers 514 (while the opposite end is unlocked). Inother embodiments, the delivery device 502 can incorporate features thatpromote a more rapid release of the tethers 514. For example, FIG. 12Aillustrates a portion of an alternative embodiment primary shaft 570useful with the delivery device 502 (FIG. 10A) described above, alongwith one tether 572. The primary shaft 570 forms a plurality of sidelumens 574 along with a central guide lumen 576. The tether 572 can havea more rigid instruction (e.g., a thin metal wire), and is arrangedrelative to a distal side 578 of the shaft 570 to define a looped end580. Commensurate with the above descriptions, the looped end 580 isconnected to a corresponding feature of the prosthetic heart valve stentframe (not shown), such as the crowns 556 (FIG. 10A). Regardless, firstand second segments 582, 584 are defined as extensions from the loopedend 580, and are routed through respective ones of the side lumens(labeled as 574 a, 574 b in FIG. 12A).

The looped end 580 of the tether 572 can be advanced in the distaldirection, for example, to release tension developed in the tether 572.In the view of FIG. 12B, the looped end 580 (referenced generally) hasbeen distally advanced from the primary shaft 570. FIG. 12B furtherreflects that the tether 572 forms a joint 586 along the first segment582. The joint 586 effectively divides the first segment 582 into aproximal region 588 and a distal region 590. The proximal and distalregions 588, 590 are connected to one another at the joint 586, with aconfiguration of the joint 586 being such that when located within theside lumen 574 a, the proximal and distal regions 588, 590 cannotseparate from one another even in the presence of significant tensionalong the first segment 582 (i.e., so long as the joint 586 is withinthe primary shaft 570, the proximal and distal regions 588, 590 remainrobustly connected to one another). However, once the joint 586 isdistally located beyond the primary shaft 570, the distal region 590separates from the proximal region 588 as shown in FIG. 12C. Onceseparated, the tether 572 can completely withdraw from the prostheticheart valve stent frame (not shown) by proximally retracting the secondsegment 584 (it being recalled that the distal region 590 is connectedto the second segment 584 at the looped end 580 (referenced generally)).

Returning to FIG. 10A, the system 500 can be configured to repair anyheart valve, and in some embodiments is useful with the aortic valve.With this in mind, FIG. 13A provides a simplified representation of anaortic valve 600 taken from the vantage point of the left ventricle. Anascending portion 602 of the aorta is also identified. The aortic valve600 generally includes three leaflets 604. The system 500 (referencedgenerally) is delivered through the ascending aorta 602 in variousmanners, such as a transfemoral delivery approach. A guide wire 606 canbe employed to track the delivery device 502 to the aortic valve 600.The dilator tip 540 is positioned slightly beyond the valve 600 asshown. The location of the delivery device 502 relative to the aorticvalve 600 of FIG. 13A is further represented from the vantage point ofthe ascending aorta 602 in FIG. 13B. At this initial stage of theprocedure, the capsule 516 remains completely over the prosthetic heartvalve (hidden in the view of FIG. 13B), maintaining the stent frameassembly 506 (hidden) in the compressed condition.

The capsule 516 is then proximally retracted relative to the stent frameassembly 506 as shown in FIG. 14A. More particularly, the capsule 516 isretracted a sufficient distance to expose the support arms 552, thusallowing the support arms 552 to self-expand as shown. As a point ofreference, the arrangement of FIG. 14A is akin to that of FIG. 11Awhereby the distal end 518 of the capsule 516 remains over the proximalportion 558 of the stent frame 550, such that the proximal portion 558remains compressed and connected to delivery device 502. Further, thetethers 514 (FIG. 11A) are placed in tension, preventing the distalportion 560 (FIG. 11A) of the stent frame 550 from self-expanding. Thedelivery device 502 is then distally advanced until the support arms 552engage the leaflets 604 as shown in FIG. 14B.

Subsequently, tension in the tethers 514 is progressively lessened,allowing the distal portion 560 of the stent frame 550 to radiallyself-expand as shown in FIG. 15A. FIG. 15B provides a sectional view ofthe aortic valve 600 with the system 500 in the partial deployment stateof FIG. 15A. Where desired, the distal portion 560 can be re-collapsedby pulling on the tethers 514, permitting repositioning of theprosthetic heart valve 504 relative to the aortic valve 600.

Once the prosthetic heart valve 504 has been satisfactorily locatedrelative to the aortic valve 600, the tethers 514 are then withdrawn(FIG. 15C) followed by complete removal of delivery device 502 from theaortic valve 600. FIG. 15D illustrates final deployment of the stentframe assembly 506 to the aortic valve 600.

Although the present disclosure has been described with reference topreferred embodiments, workers skilled in the art will recognize thatchanges can be made in form and detail without departing from the spiritand scope of the present disclosure. For example, while various systems,devices and methods of the present disclosure have made reference to aself-expanding stent frame, features of the present disclosure areuseful with other stented prosthetic heart valve constructions, such aballoon-expandable stent frame. In this regard, the tethered stent frameconnections described above can be employed with a balloon-expandablestent frame, for example to facilitate a recapture operation wherebyfollowing expansion of the stent frame by a balloon, the tethers can betensioned to effectuate at least partial collapsing of a correspondingregion of the stent frame, that in turn promotes insertion (and morecomplete collapse) of an entirety of the stent frame within a recapturesheath or other component.

What is claimed is:
 1. A system comprising: a stent frame including acell structure that is defined, at least in part, by opposing, first andsecond strut segments; the stent frame having an expanded condition anda compressed condition; the stent frame further including a first barbextending from the first strut segment and a second barb extending fromthe second strut segment; and a tether positioned around the stentframe; wherein, the first and second barbs cross over one another toform a capture zone when the stent frame is in the compressed condition;further wherein the tether is secured to the stent frame within thecapture zone in the compressed condition and the tether can be releasedfrom the capture zone and released from the stent frame when the stentframe is in the expanded condition.
 2. The system of claim 1, whereinthe capture zone is completely bounded by the first and second barbswhen the stent frame is in the compressed condition.
 3. The system ofclaim 1, wherein the tether is wound about the stent frame.
 4. Thesystem of claim 1, wherein the tether is twisted about the stent frame.5. The system of claim 1, wherein a valve structure is positioned withinthe stent frame.
 6. The system of claim 1, wherein the first and secondstrut segments are integrally formed.
 7. The system of claim 1, whereina juncture of the first and second strut segments forms an angle and theangle is greater in the expanded condition than in the compressedcondition.
 8. A method of performing a therapeutic procedure on adefective heart valve of a patient, the method comprising: receiving asystem in a delivery state, the system including a prosthetic heartvalve loaded to a delivery device, the prosthetic heart valve, theprosthetic heart valve including: a stent frame maintaining a valvestructure, the stent frame defining proximal and distal sides, the stentframe further including a cell structure that is defined, at least inpart, by opposing, first and second strut segments, a first barbextending from the first strut segment and a second barb extending fromthe second strut segment; the delivery device including a handle, aninner shaft, an outer sheath forming a capsule, and a first tether,wherein the delivery state includes: the prosthetic heart valvemaintained over the inner shaft by the capsule in a compressedcondition, and the first tether connected to the stent frame within acapture zone formed by the first and second barbs; manipulating thedelivery device to guide the prosthetic heart valve through thepatient's vasculature and into the defective heart valve; transitioningthe system to a partial deployment state by proximally retracting thecapsule from the prosthetic heart valve, the partial deployment stateincluding the prosthetic heart valve expanding from the compressedcondition toward a natural, expanded condition and remaining connectedto the delivery device via the first tether; altering a tension in thefirst tether to allow a corresponding region of the stent frame toexpand toward the expanded condition; transitioning the system to a fulldeployment state, including transitioning the stent frame to theexpanded condition, which frees the tether from the capture zone; andremoving the first tether from the stent frame.
 9. The method of claim8, further comprising: prior to the step of transitioning the system toa full deployment state, increasing a tension in the first tether topartially re-collapse a corresponding region of the stent frame.
 10. Themethod of claim 9, wherein the stent frame is a self-expanding stentframe configured to self-expand from the compressed condition to theexpanded condition.
 11. The method of claim 8, wherein the first tetheris connected to the proximal side of the stent frame in the delivery andpartial deployment states.
 12. The method of claim 8, wherein the systemis configured such that the first tether self-releases from the stentframe as part of the step of transitioning the system to the partialdeployment state.
 13. The method of claim 8, wherein the delivery deviceincludes a plurality of tethers, including the first tether, and furtherwherein the delivery state includes each of the plurality of tethersconnected to the stent frame within the capture zone.
 14. The method ofclaim 8, wherein the step of altering a tension in the first tetherincludes simultaneously altering a tension in each of the plurality oftethers.
 15. The method of claim 8, wherein the delivery device furtherincludes a valve retainer carried by the inner shaft, the valve retainerconfigured to selectively receive a component of the stent frame andforming a capture feature configured to selectively maintain a portionof the first tether in the delivery and partial deployment states. 16.The method of claim 15, wherein the step of transitioning the system tothe partial deployment state includes locating a distal end of thecapsule longitudinally between the prosthetic heart valve and the valveretainer.
 17. The method of claim 16, wherein the step of transitioningthe system to the full deployment state includes locating the distal endof the capsule proximal the capture feature of the valve retainer. 18.The method of claim 17, wherein the step of transitioning the system tothe full deployment state includes the first tether self-releasing froma valve retainer body upon retraction of the distal end of the capsuleproximal the capture feature of the valve retainer.